Background and Purpose— Combined antiplatelet agents may offer additive protection over single drugs after stroke. We investigated whether platelet activation is reduced under combined aspirin and clopidogrel compared with each drug alone. Methods— In a case-crossover study, 31 patients with previous atherothrombotic or lacunar stroke who were treated with aspirin (100 to 300 mg/d) received clopidogrel (75 mg/d) and both aspirin and clopidogrel for 4 weeks. Platelet function in whole blood was studied after each treatment period and in healthy control subjects to assess activation-dependent antigens CD62p and CD63 by flow cytometry and collagen/epinephrine (CEPI-CT) and collagen/ADP (CADP-CT) closure times with the platelet function analyzer PFA-100, which investigates platelet-related function under shear stress. Results— CD62p expression and CD63 expression were not different under the 3 treatment regimens. CD63 but not CD62p expression was lower in control subjects than in stroke patients regardless of the antiplatelet treatment ( P P P =0.0009) or clopidogrel ( P =0.0074) or in control subjects ( P =0.0010), mainly because of strong prolongation in a patient subgroup (28%). Conclusions— CD63 expression reflecting the release of platelet lysosomes is consistently increased after stroke and incompletely suppressed by treatment with aspirin, clopidogrel, or both. The strong prolongation of CADP-CT under combined aspirin and clopidogrel in a patient subgroup may indicate a lower risk of thrombosis but also a higher risk of hemorrhage. The predictive value of platelet activation parameters requires investigation in prospective studies.
#1Franz Tödtling(WU: Vienna University of Economics and Business)H-Index: 38
#2Michaela Trippl(WU: Vienna University of Economics and Business)H-Index: 36
Innovation has moved to the foreground in regional policy in the last decade. Concrete policies were shaped by “best practice models” derived from high-tech areas and well performing regions. These are often applied in a similar way across many types of regions. Here an attempt is made to show that there is no “ideal model” for innovation policy as innovation activities differ strongly between central, peripheral and old industrial areas. In this paper we analyse different types of regions with ...
Background and Purpose— The aim of this study was to evaluate the time course of platelet activation after ischemic stroke and to investigate whether platelet activation and inflammation are correlated with each other. Methods— We serially determined expression of p-selectin (CD62p) and lysosome-associated membrane protein (CD63) by platelets using flow cytometry at 10 time points between days 1 and 90 in patients after ischemic stroke (n=50), in healthy subjects (n=30), and in risk factor contr...
Abstract The PFA-100 (platelet function analyzer) is a relatively new tool for the investigation of primary hemostasis. Recent studies have shown its utility as a screening tool for investigating possible von Willebrand disorder (VWD) and various platelet disorders. More recently, the PFA-100 has been shown to be valuable in monitoring desmopressin acetate (DDAVP) therapy in both VWD and platelet disorders. The PFA-100 has also been evaluated in many other studies for its utility in assessing dr...
Last. Margaret L. Rand(U of T: University of Toronto)H-Index: 32
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Summary. The Platelet Function Analyzer (PFA-100®) was used to measure platelet function in paediatric patients with destructive versus underproduction thrombocytopenia. Closure time (CT) and total volume (TV) measurements with standard 150 μm apertures discriminated between patients with similar platelet counts from 30 to 150 × 109/l. However, at platelet counts < 30 × 109/l, a 100-μm aperture (experimental) gave the best assessment of platelet function. TV results could be analysed even when C...
Background— We studied whether aspirin resistance, defined as failure of suppression of thromboxane generation, increases the risk of cardiovascular events in a high-risk population. Methods and Results— Baseline urine samples were obtained from 5529 Canadian patients enrolled in the Heart Outcomes Prevention Evaluation (HOPE) Study. Using a nested case-control design, we measured urinary 11-dehydro thromboxane B2 levels, a marker of in vivo thromboxane generation, in 488 cases treated with aspi...
Question: Among high-risk patients with vascular disease treated with aspirin, is incomplete suppression of thromboxane generation associated with an increased risk of recurrent cardiovascular events? Population: Men and women $ 55 years of age who had a history of coronary artery disease, stroke, peripheral vascular disease, or diabetes plus at least one other CV risk factor who participated in the HOPE trial which was a 2 3 2 factorial randomized controlled trial of ramipril and vitamin E. 1 D...
We determined the percentages of fibrinogen-bound and P-selectin-expressed platelets in whole blood using flow cytometry in 254 patients with various cerebral infarction subtypes, as well as in 30 age-matched controls. Patients with atherothrombotic stroke showed significant increases in both fibrinogen-bound and P-selectin-expressed platelets. Patients with lacunar stroke also showed significant increases in both of them, but the percentage of P-selectin expression was significantly lower than ...
PRINCIPLE OF THE TEST SYSTEM The instrument aspirates a blood sample under constant vacuum from the sample reservoir through a capillary and a microscopic aperture (147 μm) cut into the membrane. The membrane is coated with CEPI or CADP. The presence of these platelet activators and the high shear rates (5000 to 6000 s–1) under the standardized flow conditions result in platelet attachment, activation, and aggregation, building a stable platelet plug at the aperture.5 The time required to occlud...
Background: Despite current treatments, patients who have acute coronary syndromes without ST-segment elevation have high rates of major vascular events. We evaluated the efficacy and safety of the antiplatelet agent clopidogrel when given with aspirin in such patients. Methods: We randomly assigned 12,562 patients who had presented within 24 hours after the onset of symptoms to receive clopidogrel (300 mg immediately, followed by 75 mg once daily) (6259 patients) or placebo (6303 patients) in a...
Abstract We determined the prevalence and clinical predictors of aspirin resistance by prospectively studying 325 patients with stable cardiovascular disease who were receiving aspirin (325 mg/day for ≥7 days) but no other antiplatelet agents. We also compared the detection of aspirin resistance with optical platelet aggregation, a widely accepted method, with a newer, more rapid method, the platelet function analyzer (PFA)-100, a whole blood test that measures platelet adhesion and aggregation ...
Clopidogrel is the most common and widely used antiplatelet agent for patients with coronary artery disease following confirmation by electrocardiographic studies. The nonresponsiveness of patients to clopidogrel and the possibility of testing for clopidogrel resistance by platelet function assays (PFA) are contentious issues. Light transmission aggregometry (LTA) is considered as the gold standard test among all PFA. In this review, the most commonly used PFA used for monitoring the effect of c...
BACKGROUND The prevalence of ex vivo 'high on-treatment platelet reactivity (HTPR)' and its relationship with recurrent vascular events/outcomes in patients with ischaemic cerebrovascular disease (CVD) is unclear. METHODS A systematic review and meta-analysis was performed in accordance with the PRISMA statement. MEDLINE, EMBASE and Cochrane Library were searched for completed manuscripts until May 2019 on TIA/ischaemic stroke patients, ≥ 18 years, treated with commonly-prescribed antiplatelet t...
Background Assessment of ‘high on-treatment platelet reactivity (HTPR)’ could enhance understanding of the pathophysiology of first or recurrent vascular events in carotid stenosis patients on antiplatelet therapy.
Moderate or severe paravalvular regurgitation after transcatheter aortic valve implantation (TAVI) is frequently associated with a loss of high-molecular-weight multimers of von Willebrand factor (VWF) and a reduced VWF collagen-binding capacity. It is unclear whether this phenomenon can also be observed in patients with mild paravalvular regurgitation, and whether there are differences between patients undergoing conventional aortic valve replacement (AVR) or TAVI. We analysed the multimeric st...
Despite the evidence that some commonly used Chinese medications (CMs) have antiplatelet/anticoagulant effects, many patients still used antiplatelets combined with CMs. We conducted a nested case-crossover study to examine the associations between the concomitant use of antiplatelets and CMs and major bleeding using population-based health database in Taiwan. Among the cohort of 79,463 outpatients prescribed antiplatelets (e.g., aspirin and clopidogrel) continuously, 1,209 patients hospitalized...
Abstract Introduction The relationship between on-treatment platelet reactivity and cerebral micro-embolic signals (MES) is unknown, and has not been previously simultaneously assessed in asymptomatic and symptomatic carotid stenosis patients. Methods Consecutive eligible patients with ≥ 50% asymptomatic or recently symptomatic carotid stenosis (≤ 4 weeks following TIA/ischaemic stroke) were recruited to this pilot study. Symptomatic patients were followed up to the ‘late’ phase (≥ 3 months) fol...
Last. Robert D. Welch(WSU: Wayne State University)H-Index: 24
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Abstract Background Rapid and accurate diagnosis of patients presenting with symptoms of stroke is needed to facilitate the timely delivery of proven effective treatment for patients with acute ischemic stroke (AIS). The aim of this study was to determine whether early assessment of platelet reactivity in patients presenting with symptoms of AIS was associated with a diagnosis of AIS, transient ischemic attack (TIA), or stroke mimic. Methods This prospective study included patients with symptoms...
Last. Bernard Yan(Royal Melbourne Hospital)H-Index: 34
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BACKGROUND AND PURPOSE: Differing responses to clopidogrel following endovascular treatment of cerebrovascular diseases may increase the risk of vascular complications. CYP2C19 gene polymorphisms influence clopidogrel activity. We aimed to study the clinical impact of CYP2C19 gene polymorphisms in patients undergoing endovascular treatment. MATERIALS AND METHODS: This was a prospective, longitudinal, observational study. Information on demographics and cerebrovascular status was collected as bas...
AbstractThe majority of patients with ischaemic cerebrovascular disease (CVD) are not protected from further vascular events with antiplatelet therapy. Measurement of inhibition of platelet function ex vivo on antiplatelet therapy, using laboratory tests that correlate with the clinical effectiveness of these agents, would potentially enable physicians to tailor antiplatelet therapy to suit individuals. A systematic review of the literature was performed to collate all available data on ex vivo ...
